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NBME 23 Answers

nbme23/Block 2/Question#15

A child with septicemia has an antibiotic clearance ...

28.8

A child with septicemia has an antibiotic clearance ...

28.8

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lispectedwumbologist
That's so infuriating I stared at this question for 20 minutes thinking I did something wrong
+35

seagull
lol..my math never worked either. I also just chose the closest number. also, screw this question author for doing that.
+5

yotsubato
Why the FUCK did they not just give us a clearance of 0.1 if they're going to fuckin round it anyways...
+10

cr
in ur maths, why did u put 24h/1day and not 1day/24h? if the given Cl was 0.09L/hr/kg. I know it just is a math question, but i´d appreciate if someone could explain it.
+

hyperfukus
magic math!!!!! how TF r we supposed to know when they round and when they don't like wtf im so pissed someone please tell me step isn't like this...with such precise decimal answers and a calculator fxn you would assume they wanted an actual answer!
+1

jean_young2019
OMG, I've got the 25.92 mg/kg/day, which isn't any of the answer choices listed. So I chose the D 51.8, because 51.8 is double of 25.9......I thought I must have make a mistake during the calculation ......
+2

atbangura
They purposely did that so if you made a mistake with your conversion like I did, you might end up with 2.5 which was one of the answer choices. SMH
+1

titanesxvi
I did well, but I thought that my mistake was something to do with the conversion and end up choosing 2.5 because it is similar to 25.92
+1

makinallkindzofgainz
The fact that we pay these people 60 dollars a pop for poorly formatted and written exams boggles my mind, and yet here I am, about to buy Form 24
+3

qball
Me after plugging in the right numbers and not rounding down : https://i.kym-cdn.com/entries/icons/original/000/028/539/DyqSKoaX4AATc2G.jpg
+1

frustratedllama
Not only do you feel like you're doing sth wrong but then that feeling stays for other questions. sucks so baad
+

Fucking NBME test writers lmao

Me: "Wait... isn't the answer 25.9? How come I don't see it here."

NBME: "Oh yeah, we rounded it."

Me: "To 30? I don't see that here, either..."

NBME: "No, to 28.8"

tyrionwill
When I got 25.9 and found nothing exactly matched, I guessed that the maintenance dose might be a bit more due to the bioavailability. So this antibiotic probably was not an I.V. formula, but an oral one, with a roughly 90% BA.
+1

Hey can someone please explain this! I am not sure how to do the math, I keep getting tripped up.

mousie
Equation is Maintenance dose = (concentration at steady state) * (Clearance)
if you convert all the units to what it wanted them in (mg/kg/day) you'll get 25.92 like weird-in said above
I didn't think to round 0.09 to 0.1 of course so I guessed 2.5 assuming I must have done a conversion wrong and was off by a tenth .... BOO bad Q
+4

12Mg/ml=12mg/L
12*0.09=1.08 mg/hr/kg
1.08*24=25.92 mg/day/kg
the nearest nanswer is 28.8

submitted by wired-in(46), 2019-05-30T03:40:03Z

Maintenance dose formula is (Css

Cltau)/F where Css is steady-state target plasma conc. of drug, Cl is clearance, tau is dosage interval & F is bioavailability.Neither dosage interval nor bioavailability is given, so ignoring those & plugging in the numbers (careful to convert units to mg/kg/day): (12 ug/mL * 1 mg/1000 ug) * (0.09 L/hr/kg * 1000 mL/1 L * 24 hr/1 day) = 25.92 mg/kg/day

...which isn't any of the answer choices listed. They must have rounded 0.09 L/hr/kg to 0.1 L/hr/kg, and doing so gives exactly 28.8 mg/kg/day (choice C)